Certain polynitrato compounds and their preparation



United States Patent 3,278,578 CERTAIN POLYNITRATO COMPOUNDS AND THEIRPREPARATION Milton B. Frankel, Menlo Park, Califl, assignor toAerojet-Geueral Corporation, Azusa, Calif., a corporation of Ohio N0Drawing. Original application June 8, 1964, Ser. No. 374,234, now PatentNo. 3,228,929, dated Jan. 11, 1966. Divided and this application Sept.8, 1965, Ser. No. 529,623

4 Claims. (Cl. 260-467) This is a division of application Serial No.374,234, filed June 8, 1964, now US. Patent No. 3,228,929.

This invention pertains to several classes of novel compounds containinga plurality of nitro or nitrato groups, and to their various methods forpreparation.

It is an object of this invention to provide several groups of novelpolynitro compounds. A further object of this invention is to prepare anew class of polynitrato compounds. Another object of this invention isto pre pare new classes of compounds which are especially useful inexplosives. Still another object of this invention is to create newsynthesis techniques in the preparation of polynitro and polynitratocompounds. These and other objects of my invention will be apparent fromthe detailed description which follows.

One of the novel classes of compounds of this inven' tion are theheterocyclic polynitro compounds having the general formula:

wherein in the above formula, A is lower alkylene, preferably havingfrom 1 to about 6 carbon atoms; and n is an integer of from 1 to 2.Preferably, in the above formula, A is methylene or ethylene, and n is1.

Typical compounds within the scope of the above formula include:

l-(3,3',3-trinitropropyl)-3,5-dinitro-1,3,5-triazacyclohexane,

l-(4',4',4-trinitrobutyl)-3,5-dinitro-l,3,5-triazacyclohexane,

l-(3',3,3'-trinitropropyl)3,6-dinitro-l,3,6-triazacycloheptane,

l-(4',4',4-trinitrobutyl) -3,6-dinitro-l,3,6-triazacycloheptane.

The novel compounds of Formula I are prepared by reacting a dinitrazaalkanediol with an N-(polynitro-alkyl) amine in accordance with thefollowing general reaction wherein A and n are as defined above. In theabove reaction the N-(polynitro-alkyl) amine may be either in the formof the free amine or in the form of the amine Patented Oct. 11, 1966"ice hydrohalide salt, the latter form being preferred, especially theamine hydrochloride salt, since it is normally more stable.

The dinitraza alkanediols employed in the above reaction are preferably,although not necessarily, prepared at 0 C. to about 50 C. in situ fromstoichiometrically equivalent amounts of the corresponding dinitramineand formaldehyde prior to the addition of the amine or aminehydrochloride. This preparation involves the following reaction:

HO oH -N \CH wherein n is equal to l or 2. This procedure is mostdesirabie since it has been found that if the primary amine andformaldehyde are contacted, there readily occurs a reaction whichresults in the production of triazines and other undesirableby-products.

The Reaction II is conveniently carried out in any polar solvent inwhich the reactants are soluble, i.e., water, methanol, ethanol, etc. Itis to be understood that when the N-(polynitro-alkyl) amine reactant isin a form of the hydrohalide salt, the solvent is preferably madealkaline by the addition of a base which is more strongly basic that theN-(polynitro-alkyl) amine and which is capable of converting the aminehydrochloride to the free amine. Typical bases which will liberate thefree amine are sodium hydroxide, potassium hydroxide, lithium hydroxideand salts of a strong base and a weak acid, such as sodium acetate.

The proportions of the reactants employed are not critical. Normally,stoichiometrically equivalent amounts are used since this results in themost complete utilization of reactants. The reaction temperature shouldnormally be sufliciently high so that the reactants will dissolve to asubstantial degree in the reaction medium, but below the decompositiontemperature of the dinitraza alkanediol reactant. Normally, the reactionis conducted at a temperature of between about 0 C. and about C. Thepreferred reaction temperature is from about 15 C. to about 50 C.

Pressure is not critical in this reaction; therefore, while any pressurecan be used, the reaction is normally conducted at atmospheric pressure.Agitation of the reactants, such as by mechanical stirrer, whiledesirable in that it increases the reaction rate, is not a necessity.The products of Reaction II are normally solids, and may be isolated inconventional manner by filtration, evaporation, and/ or crystallization.

To more clearly illustrate this aspect of my invention, the followingexamples are presented. It is to be understood that the examples areintended as illustrative embodiments of the invention and should not beconstrued as limitative of the scope of the invention in any way. In theexamples, the percentages and parts are by weight unless otherwiseindicated.

EXAMPLE I Preparation of 1-(3,3,3'-trinitr0pr0pyl)-3,5-dinitr0-1,3,5-lriazacycl0lzexane In a IOO-ml. 3-necked flask, fitted with astirrer, and dropping funnel, was placed 2.9 grams (0.02 mole) ofmethylene dinitramine, 3.2 grams (0.04 mole) of 37 percent formalin, and15 ml. of water. The yellow solution was stirred for 10 minutes and 4.6grams (0.02 mole) of 3,3,3-trinitropropylarnine hydrochloride was added.A solution of 1.84 grams (0.02 mole) of sodium acetate in 3; 25 ml. ofwater was added dropwise. The white solid was collected and dried, 5.0grams (71.4 percent), M.P. 120 to 128 d. Two recrystallizations fromchloroform gave white needles, M.P. 144 to 146 (1.

Analysis.Calcd for C H N O C, 20.34; H, 2.85; N, 31.64. Found: C, 20.32;H, 2.93; N, 32.36.

EXAMPLE II Preparation of 1(4',4',4-lrinitrobutyl)-3,6-dinitr0-1,3,6-triazacycloheptane In a 100-ml. 3-necked flask, fitted with astirrer, and dropped funnel, is placed 0.02 mole of ethylenedinitramine, 0.04 mole of 37 percent formalin, and m1. of water. Theyellow solution is stirred for 10 minutes and 0.02 mole of4,4,4-trinitrobutylamine hydrochloride is added. A solution of 0.02 moleof sodium acetate in about 25 ml. of water is added dropwise. The solidis collected and dried. Several recrystallizations from chloroform givesa needle-like product which is 1-(4',4,4-trinitrobutyl)-3,6-dinitro-1,3,6triazacycloheptane.

Another class of novel polynitro compounds forming a part of myinvention are those containing the trifiuoromethyl group and having thegeneral formula:

wherein X is selected from the group consisting of hydrogen and nitro, Aand A, are lower alkylene, and R is selected from the group consistingof nitro and lower alkyl. In the above formula when R is lower alkyl,the group normally contains from 1 to about 6 carbon atoms such asmethyl, ethyl, isopropyl and hexyl. The lower alkylene groups, A and Anormally contain up to about 6 carbons. Typical of these alkylene groupsare methylene, ethylene and hexamethylene.

The compounds of the above formula wherein X is hydrogen are prepared inaccordance with the following general reaction equation:

wherein R A and A' are as defined above in Formula III.

The compounds of Formula III wherein X is nitro, are prepared byreacting the product of Reaction IV with a strong nitrating agent, asshown in the following reaction equation where nitric acid is thenitrating agent:

wherein R A and A are as previously defined.

In Reaction IV above, the free amine may be used or, alternatively, theamine hydrohalide, with the amine hydrochloride being preferred.Reaction IV is ordinarily carried out in the presence of an inert polarsolvent such as water or methanol at a temperature from about C. toabout 100 C. For best results, both in terms of yield and reaction rate,this reaction is conducted in the pres ence of a basic material such assodium hydroxide, potassium hydroxide, calcium hydroxide or sodiumacetate. While not critical, the amine and the alcohol reactants areusually employed in about stoichiometric amounts.

The nitration Reaction V is commonly carried out employing concentratednitric acid at a temperature of 4 from about 20 C. to about +20 C.,preferably in the presence of acetic anhydride. Other strong nitratingagents such as nitrogen tetroxide may be used.

The products of Reactions IV and V may be isolated in conventionalmanner such as by extraction, crystallization and/or evaporation.

The following examples illustrate preparation of the compounds ofFormula III:

EXAMPLE III Preparation of 1,1,I-triflu0r0-5,5,5-trinitr0-3-azapentaneTo a solution of 1.36 grams (0.01 mole) of 2,2,2-trifiuoroethyl aminehydrochloride, 1.81 grams (0.01 mole) of trinitroethanol and 25 ml. ofwater was added dropwise a solution of 0.82 gram of sodium acetate in 10ml. of water. A brown oil separated from the solution. The reactionmixture was extracted with 25 ml. of methylene chloride. The combinedextracts were washed with water, dried, and concentrated to give 2.25grams (85.9 percent) of 1,1,1-trifluoro-5,5,S-trini-tro-2-azapentane, n1.4260.

When the foregoing example is repeated using 3,3,3- trinitropropanol inlieu of 2,2,2-trinitroethanol,1,1,l-trifluoro-6,6,6-trinitro-3-azahexane is obtained.

EXAMPLE IV Preparation of 1,1,1-triflu0r0-3,5,5,5-tetranitr0-3-azapentane 1,1,1-trifiuoro-5,5,5-trinitro-3-azapentane, 2.25 grams(0.0086 mole), was dissolved in 20 ml. of acetic anhydride and added to20 ml. of 99 percent nitric acid at 0 to 5 C. After stirring for 10minutes, the solution became cloudy and was poured onto ice. The whitesolid was collected, Washed with water, and dried, 1.7 grams (64.5percent), M.P. 50 to 55 C. Recrystallization from concentrated nitricacid gave white needles, M.P. 58 to 59 C.

Analysis.Calcd for C4H4F3N5O8I C, H, N, 22.81. Found: C, 15.59; H, 1.32;N, 21.79.

EXAMPLE V Preparation of 1,1,l-triflu0ro-5,5-dinitro-.i-azahexaneEXAMPLE VI Preparation 0 1,1,1-triflu0r0-3,5,5-trinitro-3-azahexane1,1,1-trifiu0ro 5,5 dinitro 3 azahexane, 2.2 grams (0.0095 mole) wasdissolved in 20 ml. of acetic anhydride and added to 20 ml. of 99percent nitric acid at 0 to 5 C. After stirring for 10 minutes, themixture was poured onto ice. The white solid was collected, washed withwater, and dried, 2.05 grams (77.9 percent), M.P. 81 to 82 C.Recrystallization from concentrated nitric acid raised the melting pointto 85 to 87 C.

Analysis.-Calcd for C H F N O C, 21.75; H, 2.56; N, 20.29. Found: C,22.16; H, 2.73; N, 20.07.

tend to be very sensitive to impact and to possess poor thermalstability, it is especially noteworthy that the impact sensitivity of1,1,1-trifluoro-3,5,5,5-tetranitro-3-azapentane is greater than 100cm./2 kg.

followed by reaction with nitric acid in accordance with the followinggeneral reaction equations:

wherein A is as defined above, and R and R' are lower alkyl of from 1 toabout 4 carbons. As is made apparent by these equations, the followingillustrative reactants and roducts can be involved.

TABLE II Tris (w-Hydroxyalkyl) Aminornethane Diester of Oxalic NitratingProduct Acid Agent Tris (m-hydroxyethyl) aminomethane.

Tris (whydroxypropyl) aminontethane.

Tris (w liydroxypentyl) Bis-N,Nltris (w-hydroxyethyl) methyl] oxamidehexanitratev Bis-N,N-[tris (w-ltydroxypropyl) methyl] oxamidehexanitrate.

Bis-N,N-[tris (w-liydroxypentyl) methyl] oxamide hexauitrate.

Diethyl oxalatc I'INO H" Dipropyloxalatc IINO aminomethane.

TABLE I Impact Calculated Calculated Sensi- Lead Block BallisticCompound tivity Value Mortar Value (TNT =100) (TNT: 100) If 0 z N O 2CI'I3-CII2-N-CII2 (|3NO2 158 154 (3,5,5,5-tetranitro-3-azapentaue) I O 21T0 2 OFs-OIIz-N-CII2-CNO2 100 164 146(1,1,1-trifluoro-3,5,5,5-tetranitro- 3-azapcntane) t or rOFH-CHrN-Om-C-CHB 100 113 127 (1,1,l-trifluoro-fi,5,5,5-triuitro-3azahexane) The impact sensitivity numbers appearing in the table referto the drop height in centimeters of a 2 kilogram weight at which 50percent of the trials resulted in an explosion.

Still another new group of compounds prepared according to my inventionare the polynitrato compounds having the general formula:

wherein the A groups are lower alkylene, preferably having from 1 toabout 6 carbon atoms.

These compounds are prepared by reacting a tris(w-hydroxyalkyl)aminomethane with a diestcr of oxalic acid,

In Equation VII, the tris (w-hydroxyalkyl) aminomethane and the diesterof oxalic acid are generally, although not necessarily, used in aboutequivalent amounts (two moles of the former per one mole of the latter).The reaction between these two materials is usually accomplished in asubstantially inert solvent such as water or the alkanols at atemperature of from about 20 C. to about 250 C.

The nitration of the N,N-[tris (w-hydroxyalkyl) methyl] oxamide can becarried out over a wide range of temperatures. It is preferred that thenitration take place at temperatures of from about -20 C. to about +30C., using up to a slight stoichiornetric excess of concentrated nitricacid.

All of the reactions of Equation VII are, in the usual case, carried outat a pressure of about one atmosphere. However, pressures both above andbelow this are envisioned. The products of these reactions are normallysolid at room temperature and may be collected in conventional manner byfiltration or evaporation, and purified by washings andrecrystallization. Prior to use in explosives, it is best that thesematerials be thoroughly dried, such as by placing them in an enclosurecontaining a drying agent such as potassium hydroxide.

The new compounds of Formula VI are, as can be seen, prepared frominexpensive commercially available materials. These compounds are usefulas high explosives and as hypotensive agents similar to the use ofnitroglycerin.

The following example illustrates the preparation of the compounds ofFormula VI.

EXAMPLE VII Bis-N,N-[lris (hydroaymethyl) methyl] oxamide hexanitratc6.5 hours. grams (96.7 percent), MP. 224 to 225 C.

3-necked flask, fitted with a stirrer and thermometer, was placed 300m1. of technical 99 percent nitric acid. The acid was cooled to C. and29.6 grams (0.1 mole) of bisN,N-[tris (hydroxymethyl) methyl] oxamideWas added. The reaction mixture was stirred for one hour at 0 C. andpoured onto ice. The white solid was collected, washed with water, anddried in vacuo over potassium hydroxide, 54.6 grams (97.3 percent), M.P.160 to 161 C. Recrystallization from ethylene dichloride did not raisethe melting point.

Analysis.Calcd for C H N O C, 21.21; H, 2.49; N, 19.79. Found: C, 21.49;H, 2.75; N, 19.01.

Calcd Lead Block Value=l46 (TNT lOO).

Calcd Ballistic Mortar Value=l33 (TNT=100).

EXAMPLE VIII Bis-N,N'-[tris (w-hydro xpropyl) methyl] oxamid ehexanitrate A mixture of 0.01 mole of tris (w-hydroxypropyl)aminomethane, 0.05 mole of dibutyl oxalate, and 200 ml. of absoluteethanol is refluxed for about 6 to 7 hours. The white solid is collectedand dried. In a 500-ml. 3- necked flask, fitted with a stirrer andthermometer, is placed about 300 ml. of technical 99 percent nitricacid. The acid is cooled to 0 C., and 0.1 mole of bis-N,N- [tris(w-hydroxypropyl) methyl] oxamide is added. The reaction mixture isstirred for about one hour at 0 C. and poured onto ice. The white solidis collected, washed with water, and dried in vacuo over potassiumhydroxide. Recrystallization from ethylene dichloride did not raise themelting point of the bis-N,N-[tris (w-hydroxypropyl) methyl] oxamidenitrate.

The new compounds of my invention, which contain a plurality of nitro ornitrato groups, are inherently useful as high explosives. Thesecompounds can also be used in any conventional explosive missile,projectile, rocket, or the like, as the main explosive charge. Anexample of such a missile is disclosed in United States Patent2,470,162, issued May 17, 1949. One Way of using these high explosivecompounds in a device, such as disclosed in United States Patent2,470,162, is to pack the explosive in powder form into the warhead ofthe missile. Alternatively, the compound may be first pelletized andthen packed. The liquid compounds can be first absorbed on cotton orsawdust, and then compacted. A charge thus prepared is sufficientlyinsensitive to withstand the shock entailed in the ejection of a shellfrom a gun barrel or a rocket launching tube under the pressuredeveloped from ignition of a propellant charge and can be caused toexplode on the operation of an impact or time-fuse mechanism firing adetonating explosive such as lead azide or mercury fulminate.

It will be understood that various modifications may be made in thisinvention without departing from the spirit thereof or the scope of theappended claims.

I claim:

1. Compounds of the formula:

wherein the lower A groups are lower alkylene.

2. The compound bis N,N-[tris (hy-droxymethyl) methyl] ox'amidehexanitrate.

3. The method of preparing polynitrato compounds of the formula:

NOaO-Az H o 0 H AzONOz I II II NO20-A2-CNCO-NCA2ONO2 NOzOA AzONO2 whichcomprises reacting a tris-(w-hydroxyalkyl) aminomethane of the formula:

HOA2

HOA2CNH2 H OA2 with a diester of oxalic acid of the formula:

to form a bis-N,N'-[tr-is (w-hydroxyalkyl) methyl] oxamide of theformula:

References Cited by the Examiner UNITED STATES PATENTS 3,238,245 3/1966Reedy 260-467 BENJAMIN R. PADGETT, Acting Primary Examiner. L. A.SEBASTIAN, Assistant Examiner.

1. COMPOUNDS OF THE FORMULA: 